Wow! How many feet above normal rest is that? Looks like the wingtip is above the top of the fuselage! Will they stress the wing until it breaks? How many feet of "flex" is considered to be acceptable? Are there actual flight situations during which the wings would flex that much?

Wow - four questions in one paragraph! Hope they don't make me sound like too much of an idiot.

I remember seeing the Boeing test on the documentary about the 777 development. Wasn't that one of the largest deflections that had ever done? I remember it bent petty far before breaking. I imagine the sound when that wing gave was just extremely loud!

BTW, it doesn't go like "the more the wing can flex - the better". Rather, aircraft manufacturer have to comply with the requirements plus and want a safety margin in case they increase the MTOW of the aircraft in question.
If the wing could withstand even higher forces, it would mean that the wing is heavier than necessary.

I'm confused. Someone mentioned plastic... is that a composite model, or is it metal? And, what do they do, just build a wing and brake it (I've heard of wing stress tests, but have never seen pics). What do they use, a jack like thing to bend it up? Or do they add weights to the end, and weigh it down? Also, what are the built in safety constrainsts? Is it designed like a car, where the pieces will fall out neatly, and not shatter/potentially destroy the fuselage?
Sorry for all the ?s

Quoting UA772IAD (reply 12):I'm confused. Someone mentioned plastic... is that a composite model, or is it metal?

I don't know how much of the 380 is composite and how much metal. But I think I read about 30-40%, but I am not sure. I only know that the main frame is made out of a very new kind of aluminium-sandwich-structure, which is much lighter than the older materials. Perhaps you can find more on the Airbus page.

Wow! I'm not sure I want to see my wing flex 6.8 meters... that probably means I'm bouncing back the same amount in the other direction!

Did anyone see the video of the similar F-14 Tomcat wing test? When the wing broke, it launched the aircraft up to the hanger roof!

NoUFO is absolutely correct in that any extra flex beyond the requirements is extra weight that just won't benefit anyone over the life of the airframe (except OPEC). I'm posted before that an airframe is worth $500/kg less to an airline for every extra bit of mass that isn't adding value to a customer.

I'm confused. Someone mentioned plastic... is that a composite model, or is it metal?The wing spars are metal, and they're all that really count here.

And, what do they do, just build a wing and brake it (I've heard of wing stress tests, but have never seen pics).They build a whole plane apart from the engines and various hydraulic/electrical parts, then stress test it.

What do they use, a jack like thing to bend it up? Or do they add weights to the end, and weigh it down?They actually use dozens of points along the wings and pull at them with jacks. At the same time, the fuse is held still with large hold-downs. The wings are flexed up and down repeatedly and finally pulled to breaking point.

Also, what are the built in safety constrainsts? Is it designed like a car, where the pieces will fall out neatly, and not shatter/potentially destroy the fuselage? If 1 is the absolute max that the plane is expected to experience in service (really bad turbulence/windshear), the structure has to hold up to 1.5 (50% stronger), and typically there is a bit more margin built in.
Seeing as this will never actually happen in service, the wing spars break catastrophically when they do break. The engineers can predict rather accurately at which load they will break, and along which cross member.

"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

Am I the only that thinks the test is more to impress the maintream media than to actually confirm that the wing is indeed solid. I mean, it's a pretty cool show but... you know...

...like the frozen-chicken-blasted-into-engine test... Great show I say.. but how many frozen chickens will an engine ingest in it's natural life? Granted, chickens WILL be frozen at 30 000 feet and up? How many african families are in dire need of those chickens? They would thaw pretty fast down there...

I say used the frozen chicken cannon where it is more needed in others parts of the planes... like those tray-table latch-thingies... or lavatory doors (Push...dumbass...push...).

Am I the only that thinks the test is more to impress the maintream media than to actually confirm that the wing is indeed solid

Knowing the structural limits of the wing is an extreme way to confrim the accuracy of your design team. It also gives valuable data as to the exact load limits of the wing, which can later dictate growth variants of the aircraft (i.e A388F, A389)

The engineers can predict rather accurately at which load they will break, and along which cross member.

I think for the 777, engineers were within a few centimeteres of the exact point where the spar fractured.

Someone mentioned plastic... is that a composite model, or is it metal?

Composite = any fiber layered with a resin. This is not plastic, but people call it plastic because they are ignorant

I believe the A388 wing is an aluminum-lithium alloy, while the fuselage is an aluminum-fiberglass hybrid called GLARE.

Also, what are the built in safety constrainsts? Is it designed like a car, where the pieces will fall out neatly, and not shatter/potentially destroy the fuselage?

The wing literally explodes... very violent afair. Hence why no one is allowed near the aircraft during the test, and those conducting the test are practically in a bunker.

The bird ingestion test birds are thawed before being shot into the engine. There are other tests as well, such as blowing off a fan blade.

Yes, airframes are stress tested. This is done both for fatigue, where cycles are simulated with applied loads and pressurisation of the fuselage. Great care is taken to get a representative sample of load cycles for these tests. It takes decades to run these tests, they are running while the aircraft are in service. The point is to have any fatigue problems show in the fatigue test rigs before they show up in operation aircraft, so that you can take preemptive measures on the operational aircraft. You also use the results of these test to successively extend the fatigue life of the airframes.

Then you have the limit load tests, which are not staged as media events at all. Finally, you break the structure to see how well it corresponds to your predictions. At times, artificial damage is introduced beforehand to verify the effects on the breaking loads.

It has happened more times than mentioned here that the test equipment gave in before the structure being tested.

I thought I was doing good trying to avoid those airport hotels... and look at me now.

Am I the only that thinks the test is more to impress the maintream media than to actually confirm that the wing is indeed solid

Not the case. The tests are necessary for certification. They also confirm the calculations made. Sure, the computer model told you x, but what if your model is incorrect? Going out there and bending metal is the only way to really know.

"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

The ultimate stress testing frame and the fatigue testing frame are both assembled by now as far as I know... And both are fully manufactured airframes, just without any non-structural systems or elements (no engines, landing gear, hydraulics, electric systems, cockpit or other interior). In exchange for that, they´ve got a huge number of additional stress simulation attachment points and a ton of sensors (quite possibly literally a ton of them...)

I´ve read that the ultimate breaking point is expected when A380 wing tips will have been pulled up by about ten meters!

One of the things to be tested will be the stability of the (first ever) composite center wing box to which the wings are attached... I have no doubts that it will hold until the wings break, but it has to be verified nevertheless...

Do you think a video of the breaking of this wing will be available publicly, or do the manufacturers keep it secret. Let's look at the situation where average Joe sees a video of a wing breaking and almost exploding. I don't think he'll ever feel safe again on a plane.

It would be really cool if they would make highspeed-films (or whatever you call these) of the moments the wing breaks available, that would be cool, seeing frame for frame what happens.

Quoting Stoney (reply 26):It would be really cool if they would make highspeed-films (or whatever you call these) of the moments the wing breaks available, that would be cool, seeing frame for frame what happens.

Check out "21st Century Jet". It's a PBS documentary about the building of the 777. In it, they show exactly what you're talking about....and if I remember correctly, they even replay it in slow-motion.